Virgin Galactic made headlines around the world this week when Richard Branson’s newest, meanest rocket plane touched the limits of space, 82 km above the Mojave Desert of California. But what does that really mean?
In a world where luxury yacht speculation is a booming business, Virgin founder Richard Branson should be proud of what his fortune achieved this Friday. Four years after the tragic crash of the first prototype, SpaceShipTwo finally breached the USAF-determined ‘edge of space’, winning astronaut wings for the pilot and setting off what I’m sure continues to be a breathtakingly lavish party.
But beneath the hype, the successful test flight of the VSS Unity is both more and less impressive than it seems. Let’s run down the trues and not-so-trues of Virgin Galactic’s red-letter day.
Pro: SpaceShipTwo really is a rocket ship
…but it’s a pretty weird one.
Technically, it’s what they call a ‘rocket plane’. While the lift force that keeps it off the ground is generated with wings like any other plane, the thrust that gets it moving comes from an honest-to-God rocket engine.
Now, you may have a picture in your head of flames shooting out of the back of fighter planes. Fire, however, does not a rocket make. The question is where the ‘propellant’ is coming from. Planes are like fish, drawing in the fluid they move through and pushing it behind them to surge forward. Rockets, by contrast, carry their own propellant, shooting it out the back really fast until they run out.
One consequence of this is that rockets can move through a vacuum, unlike planes (and no – just carrying a bubble of air around you does not evade this limitation). This is the basis of Richard Branson’s argument that SpaceShipTwo is a real spaceship – even though…
Con: The VSS Unity didn’t really go to ‘space’
What do we really mean when we talk about space?
A lot of people have in their mind a picture of the Earth as a Glad-wrapped ball: inside is air and water and Disneyland; outside is space and planets and Daleks. But in actuality, there is no hard ‘edge’ to our planet or to any other, but rather layers of gas and dust that gradually thin out with distance from the centre.
That’s not to mention the force of Earth’s gravity, which is measurable even at a distances of millions of kilometres – that’s what keeps the Moon from wandering off. (Astronauts float around because they are perpetually falling, not because there’s no gravity in space.)
Virgin Galactic’s space claim is based on the US Air Force ruling that all pilots who travel above an altitude of 80 kilometres may be called astronauts. Hence the VSS Unity was piloted by an astronaut, hence it is a spaceship – Q.E.D.
But the rest of the world uses a definition of 100 kilometres instead: what they call the Karman Line. This is the altitude at which an ordinary plane would have to move so fast to generate lift that it would reach orbital velocity and become a satellite. Below the Karman Line, all the ordinary assumptions of aeronautics apply: above the line, the rules completely change.
SpaceShipTwo didn’t make it that high and it isn’t designed to. But there’s nothing in the concept that makes it impossible. More fuel, a lighter frame, and a bit more oomph in the engine could get it into orbit.
But at that point, you might as well drop the ‘plane’ bit and just build a rocket.
Bonus: why flat-earthers won’t be convinced
At the risk of sounding pedantic, I just wanted to chuck in something which bothers me every time commercial spaceflight is discussed. SpaceShipTwo may be many things, but one thing it isn’t is a way of proving the Earth is round.
The Earth is definitely round. I’m just saying, going to a great altitude is the worst way to prove it.
Imagine if I replaced the moon with a flat disc whose face is always pointed to Earth. Would you be able to tell the difference? Unless your eyes are spaced ten miles apart, I doubt very much that you could.
The reality is that you can’t learn something new about an object’s dimensions by moving parallel to them. Flat Earthers aren’t alleging that the Earth is square. (Okay, some of them are). They agree it’s round – just the healthy, God-fearing ‘flat’ sort of round, not the heretical three-dimensional kind. And no matter what the news tells you, there is no height you can get to where you can ‘see the curvature of the Earth’.
The best way to prove the Earth is round is actually to stay as close to the surface as possible. Things in the distance will appear to vanish over the horizon – bottom first. Our distant ancestors, who spent a lot more time looking at the horizon than we do, would have noticed this phenomenon tens of thousands of years before space travel became a thing. Flat Earthism isn’t an old idea – it’s a new-fangled one which even cavemen would have laughed at.
Now, someone go tell Steph Curry that.
Unimpressed by Richard Branson’s space exploits? Read these Three reasons why the Moon still matters.
Intrigued about the hidden truth of the cosmos? Salivate over the imminent apocalypse on Nibiru – the Shadowy Death-Planet.